a. Field of the Invention
The present invention relates to systems and methods for manufacturing molded plastic members, and particularly molded plastic siding products. As used herein, “molded” refers to any suitable process by which the shape or configuration of the plastic product is formed or altered, including, for example, vacuum forming, injection molding, pressing or stamping, casting, extruding, embossing, etc.
b. Description of the Related Art
It is known to extrude or form a sheet or strip of plastics material such as, for example, a vinyl or other thermoplastic material, and then direct the sheet or strip between a pair of rolls to emboss a pattern or surface texture into at least one surface thereof, usually the surface eventually defining an exterior surface of the product. Embossed products manufactured using such a process are typically elongate, and the embossed patterns typically simulate wood grain, natural stone, stucco, etc.
A typical prior method for embossing a pattern in vinyl siding products involves running a hot sheet or strip of plastic received from an extrusion die through a nip roll setup that includes a pair of cooperating rolls. One of the rolls is the embossing roll and has a steel circumferential surface in or on which the reverse image of the desired texture is formed. The other roll is the backing roll, and is normally steel with a heat resistant, hard rubber circumferential coating.
The elongate member while still pliable may be formed or reshaped into a desired configuration (e.g., shaped into an L-shaped or J-shaped cross section) subsequent to being embossed with the exterior surface texture. Further subsequent processing may include snipping, sawing, or punching operations, generally after the material has further stabilized.
The textures imparted to these products by the embossing process may define a surface in the molded part that has variation associated with natural building products such as wood or stone, and may include associated peaks, valleys, grooves, grain, . . . etc. . . . , but these surface features, although discernable and contributing the aesthetics of the product, tend to be generally smooth, rather than substantially rough. This is due to limitations of the embossing systems and processes employed in prior systems and methods for manufacturing molded plastic products of this type. Thus, the roughness of the resulting molded surface can be substantially limited.
Although there are some instances where a molded plastic siding product is desired that has a discernable aesthetic surface pattern or texture which is substantially smooth (e.g., where fine grained wood or smooth stone is being simulated), it would oftentimes be preferable to use siding products having a substantially rougher surface texture than that which can be had in molded plastic siding products embossed using prior manufacturing systems and processes. That is, a molded plastic siding product having a surface texture that is substantially rougher vis-à-vis prior such products is desirable in some instances. Such comparatively rougher-surfaced molded plastic products may better simulate the appearance of, for example, natural building elements such as natural stone or rough-hewn wood.